We are developing an MHC-haploidentical allogenic bone marrow transplantation model that parallels human treatment and can be used to decipher the immunologic impact of post-transplantation cyclophosphamide. We are studying the impact of this therapy on clinical endpoints (survival, graft-versus-host disease, weight); accompanying these studies is a detailed characterization of the immunologic and histopathologic changes associated with this approach. Once the model is fully characterized, we will use this as a basis to explore how the approach can be modified to further reduce graft-versus-host disease, ensure reliable engraftment with minimal conditioning, and serve as a platform for other therapies to reduce relapse.